Inhibition of in vitro capacitation of hamster spermatozoa by nitric oxide synthase inhibitors
Kameshwari, D.B.; Siva, A.B.; Shivaji, S.
Cellular and Molecular Biology 49(3): 421-428
2003
ISSN/ISBN: 0145-5680 PMID: 12887095 Document Number: 555119
In an attempt to understand the role of nitric oxide (NO) in sperm capacitation, in the present study, hamster spermatozoa were used to evaluate the effects of NO on motility, viability, hyperactivation, capacitation and protein tyrosine and serine phosphorylation using specific inhibitors of nitric oxide synthase (NOS); namely L-NAME (N-nitro-L-arginine methyl ester) and 7-Ni (7-nitroindazole). The results indicated that L-NAME inhibits sperm motility, hyperactivation and acrosome reaction where as 7-Ni inhibits only hyperactivation and acrosome reaction thus implying that NOS inhibitors exhibit subtle differences with respect to their effects on sperm functions. This study also provides evidence that NOS inhibitors inhibit sperm capacitation by their ability to modulate protein tyrosine phosphorylation. However, the inhibitors had no effect on the protein serine phosphorylation of hamster spermatozoa during capacitation. Thus, these results indicate that NO is required.